A Three Level LC-Switching Based Voltage Boost NPC Inverter

Abstract– Single stage high voltage gain boost inverter is getting popularity in applications like solar-PV, fuel cell, UPS systems etc. Recently, single stage voltage boost multilevel Z-Source inverter (ZSI) and Quasi Z-source inverter (QZSI) have been proposed for DC-AC power conversion with improved power quality. Multilevel ZSI uses more number of high power passive components in the intermediate network which increase the system size and weight. Also its input current is discontinuous in nature which is not desirable in some of the applications like fuel cell, UPS systems, hybrid electric vehicle etc. In addition, a continuous current input three level LCSwitching based voltage boost neutral point clamped (NPC) inverter is proposed which uses comparatively less
number of high power passive components at the same time retains all the advantages of multilevel QZSI/ZSI. It is able to boost the input DC voltage and give required three level AC output voltage in a single stage. Steady state
analysis of the proposed inverter is discussed to formulate the relationship between the input DC voltage and three level AC output voltage. A unipolar PWM technique devised for the proposed inverter to eliminate first center band  harmonics is also presented. The proposed converter has been verified by simulation in MATLAB Simulink as well as performing experiment with the help of a laboratory prototype.